Firefly Populations Are Blinking Out

Blink and you’ll miss them this summer. Around the world, people are reporting that local firefly populations are shrinking or even disappearing.

The insect’s dilemma first came to the world’s attention at the 2010 International Firefly Symposium, where researchers from 13 nations presented evidence of firefly population declines and declared “an urgent need for conservation of their habitats.” Since then, additional conferences and several scientific papers have documented regional firefly disappearances, and at least two citizen-science projects are attempting to document the phenomenon, but the full scope of the problem remains to be uncovered, says firefly researcher Ben Pfeiffer, founder of Firefly.org, a website about the decline of the insects, also called lightning bugs.

“It’s worrying,” said Pfeiffer. “When people see a habitat that’s got three, four, five different species of firefly flashing, each with a different flash pattern, it’s an amazing thing. It changes their lives, but few people get to see that anymore.”

The exact extent of the decline is unknown, but early indications suggest that lightning bug populations have shrunk in many places and disappeared from others. “Everyone is reporting declines,” said Eric Lee-Mӓder, codirector of the pollinator program for the Xerces Society for Invertebrate Conservation.

Lee-Mӓder said he suspects that decades of overzealous collection by the medical industry may have also contributed to fireflies’ decline. Pharmaceutical companies used to pay bounties of up to a penny per firefly to collect their chemicals for biomedical use. The pharmaceutical company Sigma Chemical Company collected up to 1 million fireflies a year and sold the chemicals for about $260 an ounce, according to a 1975 report in the Milwaukee Journal.

“If you do the math, that’s a lot of insects,” Lee-Mӓder said. “You multiply that over a pretty wide area and add these other stress factors, and there’s no doubt that it has had a major impact on populations. We just don’t know what that impact is yet.”

A 2013 study published in Ecological Modeling found that some firefly populations failed when medical harvest rates exceeded 60 percent.